Donald T. Campbell
Better knowledge needs better designs and honest doubt.
American social scientist known for research methodology, validity and program evaluation.
Better social knowledge requires better designs, better validity and humility about causal claims.
Who they were
Donald Campbell asked the hard question behind every claim: how do we know? He developed ways to study cause in the messy real world, distinguished kinds of validity, and warned how easily measures get gamed. His work gave social science tools for rigor and a habit of humility about its conclusions.
Famous books
What they left on the shelf
Terms they cared about
Ideas worth knowing
Their techniques
How the work was done
Best known as a theorist — their ideas shaped the techniques of those who followed.
Their big idea
Validity Theory
Donald Campbell distinguished internal validity (does the study support a causal claim?) from external validity (does it generalize?), and championed quasi-experimental designs for studying cause where true experiments are impossible.
Questions in their spirit
What they’d ask you
Sit with one. Answer online, or in the app.
Carry the idea forward
Campbell — What they’d ask you
Psipas asks you one small, honest question at a time — and builds the picture from your answers.